Colloq Abstract - Andernach

Dec 15

11:00am Mountain

 

Heinz Andernach (Universidad de Guanajuato)

 

Giants all over: The Ubiquity of Mpc-scale Radio Galaxies

 

Abstract

Giant radio galaxies (GRGs) have projected linear sizes exceeding 1 Mpc.  Only about 300 GRGs have been reported, in several dozens of papers.  Since 2012 our search for new GRGs via visual inspection and automated algorithms of NVSS, WENSS, FIRST, SUMSS, TGSS-ADR1 and other survey images, as well as results from Radio Galaxy Zoo (RGZ),

have increased the number of GRGs to over 1200. We doubled the number of GRGs above 4 Mpc and have found some candidates over 5 Mpc size.  Our follow-up with optical spectroscopy, plus JVLA imaging, has confirmed several dozen new giants, as well as the general reliability of photometric redshifts. While the median redshift of published GRGs is 0.25, our new GRGs and those of RGZ achieve a median z of 0.6, including about 15 QSOs at redshifts from 2 to 5.

I will show examples of the relative ease to find new GRGs, especially with simultaneous coverage of NVSS, FIRST, SDSS, and, since very recently, the ongoing 3-GHz VLA Sky Survey.  GRGs show a large variety of radio morphologies, and I explore some statistical trends for lobe symmetry and compactness of their emission. Their host galaxies show all possible activity types, with LLAGNs dominating at low redshift and QSOs and Sy1's at high redshift. No significant trend of radio size with redshift is seen, posing a problem for standard cosmology.

 

 

Connect with NRAO

The National Radio Astronomy Observatory and Green Bank Observatory are facilities of the U.S. National Science Foundation operated under cooperative agreement by Associated Universities, Inc.

Founded in 1956, the NRAO provides state-of-the-art radio telescope facilities for use by the international scientific community. NRAO telescopes are open to all astronomers regardless of institutional or national affiliation. Observing time on NRAO telescopes is available on a competitive basis to qualified scientists after evaluation of research proposals on the basis of scientific merit, the capability of the instruments to do the work, and the availability of the telescope during the requested time. NRAO also provides both formal and informal programs in education and public outreach for teachers, students, the general public, and the media.

The National Science Foundation (NSF) is an independent federal agency created by Congress in 1950 "to promote the progress of science; to advance the national health, prosperity, and welfare; to secure the national defense..."

AUI collaborates with the scientific community and research sponsors to plan, build, and operate cutting-edge facilities. We cultivate excellence, deliver value, enhance education, and engage the public.